1. Field of the Invention
The present invention relates to a method of manufacturing ceramic products, and also to a method of manufacturing ceramic springs.
2. Description of the Related Art
Ceramic products are greatly resistant to heat, corrosion, and wearing. However, sintered ceramic products scarcely undergo plastic deformation. They are hard and brittle, and are extremely difficult to machine. Hence, when sintered ceramic bodies are machined into products of desired shaped, the resultant product will inevitably be expensive due to the cost of machining the sintered ceramic bodies.
To manufacture ceramic products at low cost, ceramic bodies should be machined as little as possible once they have been sintered. To this end, a mixture of ceramic materials are first shaped, or shaped and calcined, and then machined.
Various methods of shaping ceramic materials have been used, in accordance with the mechanical and physical properties which ceramic products should have, and also in accordance with the cost at which the products should be made. Among these methods are: slip casting, die pressing, isostatic molding, injection molding, extruding, and doctor-blade method.
Die pressing is advantageous in two respects. First, it can make shaped products greatly precise in size. Secondly, it can manufacture shaped products with a high efficiency, and thus is suitable for mass production. However, die pressing is accompanied with several problems: (i) the shaped products by this method are likely to fail to have a uniform density; (ii) the method requires very hard dies; (iii) the dies required in the method are very expensive; and (iv) a high pressure must be applied in this method.
Isostatic molding is advantageous in two respects. First, a pressure is applied on a ceramic mixture body uniformly, and the resultant shaped products can cardly fail to have a uniform density. Secondly, rubber molds, which are inexpensive, can suffice. Isostatic pressing is, however, disadvantageous in that the shaped products have rough surfaces, unlike those made by die pressing, and must be subjected to machining.